A great deal of prior work has been done on the phenol-formaldehyde resin system. These resins are valuable for use in preparing various thermo-setting binder materials. Phenol-formaldehyde resins constitute a principal binding agent for mineral fibres, such as glass fibres, imparting integrity of shape and physical properties to the finished product. In the majority of cases they are applied in aqueous solution.
In the manufacture of mineral fibre insulation products, phenol-formaldehyde resins in binder material are usually applied either in an unpolymerized, or initially polymerized or intermediate stage of polymerization. The binder material is subsequently sprayed onto the fibres to form a fibre-resin pack. The pack is advanced to a cured stage upon activation by heat and/or catalysts with or without the application of pressure for densification of the composite mass into a board or molded form of the desired configuration. Typically, the thermo-setting resins are phenol-formaldehyde condensation products of the resol type, such as described in Canadian Pat. No. 1,080,871 and U.S. Pat. No. 3,932,334 (reissued as U.S. Pat. No. Re. 30,375) of the same assignee, the disclosures of which are hereby incorporated by reference.
Binder systems for binding mineral fibre products usually contain, in conjunction with the phenolic resins and water substances such as modifiers, e.g. extenders, coupling agents, dyes, processing oils, ammonia, and, occassionally, other additives. Binders of this type are disclosed in Canadian Pat. No. 1,001,788 of the same assignee, the disclosure of which is hereby incorporated by reference.
It is customary in preparing prior art glass fibre resin-impregnated insulation materials to minimize the amount of resinous binder which is employed to thereby secure economic savings. However, the use of low amounts of binder results in reduced mechanical properties, whereas in general the use of higher amounts of binder results in better mechanical properties. Frequently, amide type compounds, such as urea, dicyandiamide or melamine, or water-miscible condensation products of these amide type compounds with formaldehyde are used as modifiers or extenders.
These additives may reduce the release of volatile phenolic reaction products during application and cure of phenol-formaldehyde resins and thus reduce pollution of the air. Furthermore, it is desirable from an economic viewpoint, to find ways of reducing the costs associated with phenol-formaldehyde resins used in the manufacture of glass fibre insulation products.
The phenol-formaldehyde resins which are useful for glass fibre insulation manufacture, are most often extended with urea. The urea modifies the properties of these resins in a desirable manner and contributes to the overall efficiency and usefulness of the binder system. Over a number of years these resins and binder systems have been optimized to provide the best level of useful properties, processability and cost.
Materials which might be used to further extend these binders must be compatible with these existing binder systems, must not detract from the established properties of either the binder or product manufactured from these binders, and, of course, must also be cost effective. In addition, a potential extender must not produce a disruptive effect on the balance of the manufacturing processes which have been established and are operating.
Attempts to extend binder systems for mineral fibre products using a variety of additives and co-reactants have been made and described. The most common approach has been to add lignin compounds. These materials, indeed, extend the binders, but also shorten the gel times excessively, making it difficult to run lignin extended binders in the manufacture of many types of heavy density glass fibre products.
U.S. Pat. No. 3,336,105 to Helbing discloses the use of ammonium lignosulfonate as extender applied in conjunction with urea.
U.S. Pat. No. 4,014,726 to Fargo describes the use of starch and starch degradation products as replacement for dicyandiamide extender applied in conjunction with urea extender.
It is an object of the invention to extend phenol-formaldehyde resins, which are suitable for use in binder systems for bonding mineral fibre products, with inexpensive and effective extenders.
It is a further object of the invention to reduce the percentage of phenol required in binder systems based on phenol-formaldehyde resins by extending the resin with an amide or amine such as urea and a sugar.
It is a further object of the invention to increase the amount of amide or amine such as urea which can be used to extend a phenol-formaldehyde resin by adding to the resin mono- or oligosaccharides, or water-soluble polysaccharides.